Bond Via Array for Thermal Conductivity

ABSTRACT

In a microelectronic device, a substrate has first upper and lower surfaces. An integrated circuit die has second upper and lower surfaces. Interconnects couple the first upper surface of the substrate to the second lower surface of the integrated circuit die for electrical communication therebetween. A via array has proximal ends of wires thereof coupled to the second upper surface for conduction of heat away from the integrated circuit die. A molding material is disposed in the via array with distal ends of the wires of the via array extending at least to a superior surface of the molding material.

FIELD

The following description relates to microelectronic devices. More particularly, the following description relates to a via array for thermal conduction of heat away from an integrated circuit die of a microelectronic device.

BACKGROUND

Some integrated circuit dies may have hot spots when operated and/or may throw off more heat when operated than other integrated circuit dies. For some microelectronic assemblies, it may be problematic to conduct heat away from such integrated circuit dies due to placement next to a die stack and/or ability to target hot spots for thermal conduction away therefrom or due to placement of a die within an encapsulation mold compound which are generally poor thermal conductors.

Accordingly, it would be desirable and useful to provide for thermal conduction for an integrated circuit die that mitigates or overcomes one or more of the above-described limitations.

BRIEF SUMMARY

An apparatus relates generally to a microelectronic device. In such an apparatus, a substrate has a first upper surface and a first lower surface. An integrated circuit die has a second upper surface and a second lower surface. Interconnects couple the first upper surface of the substrate to the second lower surface of the integrated circuit die for electrical communication therebetween. A via array has proximal ends of wires thereof coupled to the second upper surface for conduction of heat away from the integrated circuit die. A molding material is disposed in the via array with distal ends of the wires of the via array extending at least to a superior surface of the molding material.

An apparatus relates generally to another microelectronic device. In such an apparatus, a package substrate has a first upper surface and a first lower surface. An interposer substrate has a second upper surface and a second lower surface. First interconnects couple the second lower surface and the first upper surface to one another. An integrated circuit die has a third upper surface and a third lower surface. Second interconnects couple the second upper surface and the third lower surface to one another. A die stack is coupled to the interposer substrate, where the die stack has a fourth upper surface higher than the third upper surface. A via array has proximal ends of wires thereof coupled to the third upper surface for conduction of heat away from the integrated circuit die. A molding material is disposed in the via array with distal ends of the wires of the via array extending at least to a superior surface of the molding material and higher than the fourth upper surface of the die stack.

A method relates generally to formation of a microelectronic device. In such a method, a substrate is obtained having a first upper surface and a first lower surface. An integrated circuit die is obtained having a second upper surface and a second lower surface. The first upper surface of the substrate is interconnected with interconnects to the second lower surface of the integrated circuit die for electrical conductivity therebetween. A via array is formed having proximal ends of wires thereof coupled to the second upper surface for conduction of heat away from the integrated circuit die. Molding material is deposited in the via array with distal ends of the wires of the via array extending at least to a superior surface of the molding material.

BRIEF DESCRIPTION OF THE DRAWING(S)

Accompanying drawing(s) show exemplary embodiment(s) in accordance with one or more aspects of exemplary apparatus(es) or method(s). However, the accompanying drawings should not be taken to limit the scope of the claims, but are for explanation and understanding only.

FIG. 1 is a block diagram of a cross-sectional view depicting an exemplary three-dimensional integrated circuit (“3D IC”) packaged component with via structures.

FIG. 2 is a block diagram of a cross-sectional view depicting another exemplary 3D IC packaged component with via structures.

FIG. 3-1 is a block diagram of a cross-sectional view depicting an exemplary microelectronic device.

FIG. 3-2 is a block diagram of a cross-sectional view depicting another exemplary microelectronic device.

FIG. 4 is a top-down perspective view of via arrays of FIG. 3-1.

FIG. 5 is a block diagram of a cross-sectional view depicting another exemplary microelectronic device, which in this example is a 3D IC packaged component.

FIG. 6 is a flow diagram depicting an exemplary process for formation of a microelectronic device, such as of FIG. 3-1, 3-2, or 5.

FIG. 7 is a block diagram of a cross-sectional view depicting another exemplary microelectronic device, which in this example is a 3D IC packaged component with an optional via array disposed on a die stack.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth to provide a more thorough description of the specific examples described herein. It should be apparent, however, to one skilled in the art, that one or more other examples or variations of these examples may be practiced without all the specific details given below. In other instances, well known features have not been described in detail so as not to obscure the description of the examples herein. For ease of illustration, the same number labels are used in different diagrams to refer to the same items; however, in alternative examples the items may be different.

Microelectronic assemblies generally include one or more ICs, such as for example one or more packaged dies (“chips”) or one or more dies. One or more of such ICs may be mounted on a circuit platform, such as a wafer such as in wafer-level-packaging (“WLP”), printed board (“PB”), a printed wiring board (“PWB”), a printed circuit board (“PCB”), a printed wiring assembly (“PWA”), a printed circuit assembly (“PCA”), a package substrate, an interposer, or a chip carrier. Additionally, one IC may be mounted on another IC.

A substrate may include an upper surface and a lower surface that extend in lateral directions and are generally parallel to each other at a thickness of such substrate. Use of terms such as “upper” and “lower” or other directional terms is made with respect to the reference frame of the figures and is not meant to be limiting with respect to potential alternative orientations, such as in further assemblies or as used in various systems.

A substrate may have a passivation level. A solder bump or wire bond may be conventionally coupled to a bond pad exposed through such passivation level. A passivation layer may be a polymer layer. For example, a passivation layer may be a benzocyclobutene (“BOB”) layer or a combination of a silicon nitride layer and a BCB layer. In some applications, a passivation layer may be referred to as an inter-die layer.

A metal layer, such as a copper, copper alloy, or other metal, may be formed on a passivation layer and on lower end contact surfaces. Balls may be respectively formed on bonding pads, where such pads may be formed on or as part of such a metal layer. Balls may be formed of a bonding material, such as solder or other bonding material. Balls may be microbumps, C4 bumps, ball grid array (“BGA”) balls, or some other die interconnect structure. In some applications, a metal layer may be referred to as a landing pad.

More recently, three-dimensional (“3D”) ICs or “3D ICs” have been formed. Generally, attaching one die to another may be performed at a bond pad level or an on-chip electrical wiring level. ICs may be diced from a wafer into single dies. Such single dies may be bonded to one another or bonded to a circuit platform. For purposes of clarity by way of example and not limitation, it shall be assumed that an interposer is used for such circuit platform.

With the above description borne in mind, FIG. 1 is a block diagram of a cross-sectional view depicting an exemplary 3D IC packaged component 50 with via structures 18. While a stacked die or a package-on-package die may include TSV interconnects, use of via structures 18 for a 3D IC packaged component 50 is described for purposes of clarity by way of example. In this example of a 3D IC packaged component 50, there are three ICs 10, namely ICs 10-1, 10-2, and 10-3, which are stacked one upon the other. In other implementations, there may be fewer or more than three ICs 10 in a stack. ICs 10 may be bonded to one another using microbumps 52 or flip-chip solder bumps. Optionally, Cu pillars extending from a backside of a die may be used. Some of these microbumps 52 may be interconnected to via structures 18. For example, a Cu/Sn microbump transient liquid phase (“TLP”) bonding technology may be used for bonding ICs to one another. Thus, interconnect layers may be on one upper or lower side or both upper and lower sides of an IC 10 of a 3D stack.

A lower IC 10-3 of such ICs in a 3D stack optionally may be coupled to an interposer or interposer die 40. Interposer 40 may be an active die or a passive die. For purposes of clarity and not limitation, it shall be assumed that interposer 40 is a passive die. IC 10-3 may be coupled to interposer 40 by microbumps 52. Interposer 40 may be coupled to a package substrate 41. Package substrate 41 may be formed of thin layers called laminates or laminate substrates. Laminates may be organic or inorganic. Examples of materials for “rigid” package substrates include an epoxy-based laminate such as FR4, a resin-based laminate such as bismaleimide-triazine (“BT”), a ceramic substrate, a glass substrate, or other form of package substrate. An under fill 54 for a flip chip attachment may encapsulate C4 bumps or other solder balls 53 used to couple interposer 40 and package substrate 41.

A spreader/heat sink (“heat sink”) 43 may be attached to package substrate 41, and such heat sink 43 and substrate package 41 in combination may encase ICs 10 and interposer 40 of such 3D stack. A thermal paste, thermal interface material (“TIM”), or other thermally conductive material 42 may couple an upper surface of IC 10-1 on top of such 3D stack to an upper internal surface of such heat sink 43. Ball grid array (“BGA”) balls or other array interconnects 44 may be used to couple package substrate 41 to a circuit platform, such as a PCB for example.

FIG. 2 is a block diagram of a cross-sectional view depicting another exemplary 3D IC packaged component 50 with via structures 18. 3D IC packaged components 50 of FIGS. 1 and 2 are the same except for the following differences; in FIG. 2, another IC 10-4 is separately coupled via microbumps 52 to interposer 40, where IC 10-4 is not coupled in the stack of ICs 10-1, 10-2, and 10-3. Furthermore, interposer 40 includes metal and via layers for providing wires 47 for interconnecting ICs 10-3 and 10-4. Furthermore, interposer 40 includes via structures 18 coupled to IC 10-4 through microbumps 52.

3D wafer-level packaging (“3D-WLP”) may be used for interconnecting two or more ICs, one or more ICs to an interposer, or any combination thereof, where interconnects thereof may use via structures 18. Optionally, ICs may be interconnected die-to-die (“D2D”), package-on-package (“PoP”) or chip-to-chip (“C2C”), where interconnects thereof may use via structures 18. Further, optionally, ICs may be interconnected die-to-wafer (“D2W”) or chip-to-wafer (“C2W”), where interconnects thereof may use via structures 18. Accordingly, any of a variety of die stacking or chip stacking approaches may be used to provide a 3D stacked IC (“3D-SIC” or “3D-IC”). One or more dies may be used to provide a system-in-a-package (“SiP”).

FIG. 3-1 is a block diagram of a cross-sectional view depicting an exemplary microelectronic device 100. Microelectronic device 100 includes a substrate, such as a package substrate 41, having a first upper surface 102 and a first lower surface 101. Microelectronic device 100 includes an integrated circuit die 10 having a second upper surface 112 and a second lower surface 111. In this configuration, integrated circuit die 10 may have a downward facing orientation.

Microelectronic device 100 includes interconnects, such as microbumps 52 or solder balls 53, coupling first upper surface 102 of package substrate 41 to second lower surface 111 of integrated circuit die 10 for electrical conductivity. An under fill 54 may be used to encapsulate microbumps 52 or solder balls 53 between surfaces 102 and 111 prior to use of a molding material 110.

Prior to deposition of a molding material 110, a via array 120 may be formed. Via array 120 may be a Bond Via Array™ or other array with spaced apart wires 123 and 124. Proximal ends 127 of wires 123 and 124 may be coupled to second upper surface 112 for conduction of heat away from integrated circuit die 10. In a configuration where integrated circuit die 10 is face up instead of face down as in this example, optionally wires 123 and 124 may be coupled to such an upward facing front side surface. However, more likely there is going to be room on a back side surface for coupling wires 123 and 124, and thus thermal dissipation. Accordingly, a downward facing front side surface orientation is described herein. By proximal ends 127, such ends are proximal to integrated circuit die 10 in comparison to distal ends 128 of such wires 123 and 124. Proximal ends 127 of wires 123 and 124 may be soldered or otherwise bonded to upper surface 112 with a bonding or soldering material to form wire bonds 125. For example, an Electronic Flame-Off (“EFO”) induced ball bonding process may be used.

In this example, an optional passivation layer 132 may be deposited or otherwise disposed on second upper surface 112 of integrated circuit die 10. A metalization layer 133 may be deposited over, including on, second upper surface 112 of integrated circuit die 10. For a configuration with optional passivation layer 132, metalization layer 133 may be deposited or otherwise disposed on passivation layer 132. Metalization layer 133 may be used for wire bonds 125 for coupling proximal ends 127 of wires 123 and 124 of via array 120 to second upper surface 112 for thermal conduction of heat away from integrated circuit die 10. Accordingly, second upper surface 112 of integrated circuit die 10 may be a back surface for a downward facing integrated circuit die 10.

FIG. 3-2 is a block diagram of a cross-sectional view depicting another exemplary microelectronic device 100. Microelectronic device 100 of FIG. 3-2 may be the same as microelectronic device 100 of FIG. 3-1 with wires or wire bonds 321 and with or without microbumps 52 or solder balls 53, as previously described. In a configuration without microbumps 52 or solder balls 53 as previously described, integrated circuit die 10 may have an upward-facing orientation. However, as integrated circuit dies 10 become more circuitry dense, there is a greater emphasis on input/output contacts, and so a downward-facing orientation of integrated circuit 10, such as for microbumps 52 or solder balls 53, may provide such input/output contacts. Along those lines, wire bonds 321 may be used for additional conduction of heat away from integrated circuit die 10. Wire bonds 321 may be respectively coupled to pads 320, which may be formed as part of metalization layer 133, at first ends thereof. Second ends of wire bonds 321 may be coupled to a bulk metal layer 322 formed in substrate 41 extending to or exposed at first upper 102 for connecting such second ends of wire bonds 321 thereto for additional thermal conduction. Such a bulk metal layer 322 may additionally be used as a ground plane.

For purposes of clarity by way of example and not limitation, microelectronic device 100 of FIG. 3-1 is further described herein; however, the following description may likewise apply to microelectronic device 100 of FIG. 3-2.

After forming via array 120, a molding material 110 may be deposited or otherwise disposed in via array 120 with distal ends 128 of wires 123 and 124 of via array 120 extending at least to, including level with and/or above, an upper or a superior surface 141 of molding material 110. A thermal paste, TIM, or other thermally conductive adhesive (“thermal paste”) 42 may be deposited or otherwise disposed on upper surface 141 to be in contact with distal ends 128 of wires 123 and 124. A lower surface 142 of heat sink 43 may be put in contact with thermal paste 42. Moreover, optionally, portions of distal ends 128 may be put in contact with lower surface 142 of heat skink 43 for thermally coupling distal ends 128 of wires 124, and optionally of wires 123, and heat sink 43. In other words, thermal paste 42 may be used to couple wires 123 and 124 to heat sink 43 for thermal conductivity. Heat sink 43 may be disposed above distal ends 128 of wires 123 and 124, and such heat sink 43 may be pushed down to form contact with such distal ends 128 during assembly, as outer angled wires 124 are bendable.

Along the above-described lines, FIG. 4 is a top-down perspective view of via arrays 121 and 122 of FIG. 3-1. Microelectronic device 100 is further described with simultaneous reference to FIGS. 3-1 and 4.

Proximal ends 127 of wires 123 and 124 of via array 120 may be for separate via arrays 121 and 122, respectively. Along those lines, proximal ends 127 of wires 123 may be of via array 121, and proximal ends 127 of wires 124 may be of via array 122. Via array 121 may be interior to via array 122. Accordingly, proximal ends 127 of wires 123 and 124 of via arrays 121 and 122, respectively, may be couple to second upper surface 112 for the conduction of heat away from integrated circuit die 10 at different rates. Along those lines, via array 121 may be denser, namely more wires 123 within an area, than via array 122. Via array 121 may be denser than via array 122, as via array 121 may be disposed over a hot spot, generally indicated as area 401, of integrated circuit die 10.

Distal ends 128 of wires 124 of via array 122 may be more widely dispersed than distal ends 128 of wires 123 of via array 121. Distal ends 128 of wires 123 may not come into direct contact with lower surface 142, while distal ends 128 of wires 124 may come into direct contact with lower surface 142 of heat sink 43.

FIG. 5 is a block diagram of a cross-sectional view depicting another exemplary microelectronic device 100, which in this example is a 3D IC packaged component. Microelectronic device 100 includes a package substrate 41, an interposer substrate 40, solder balls 53 for interconnects, an integrated circuit die 10, an integrated circuit die stack (“die stack”) 501 exclusive of integrated circuit die 10, microbumps 52 as other interconnects, a via array 120, a molding material 110, a heat sink 43, and thermal paste 42.

Package substrate 41 has a first upper surface 102 and a first lower surface 101. Interposer substrate 40 has a second upper surface 512 and a second lower surface 511. Solder balls 53 may couple second lower surface 511 and first upper surface 102 to one another. Integrated circuit die 10 has a third upper surface 112 and a third lower surface 111. Microbumps 52 may couple second upper surface 512 and third lower surface 111 to one another.

Die stack 501 may in effect have a fourth upper surface 521 and a fourth lower surface 522. Microbumps 52 may couple second upper surface 512 and fourth lower surface 522 to one another. Fourth upper surface 521 may be substantially higher or above, though not over, third upper surface 112 of integrated circuit die 10.

Optionally, a via array 550 of wires 123 may be formed on upper surface 521, as illustratively depicted in FIG. 7, with is the block diagram of the cross-sectional view depicting the exemplary microelectronic device 100 of FIG. 5 though with the addition of via array 550. Via array 550 may be formed as previously described with reference to via array 121. Moreover, optionally, for low thermal dissipation applications heat sink 43 and thermal paste 42 may be omitted and wires of via arrays 550 and 120 may effectively provide heat sink fins.

However, wires 123 of via array 120 may have distal ends 128 which extend above or higher than fourth upper surface 521. Via array 120 may further have proximal ends 127 of wires 123 thereof coupled to third upper surface 112 for conduction of heat away from integrated circuit die 10. Proximal ends 127 of wires 123 may be soldered or otherwise bonded to third upper surface 112 with a bonding or soldering material to form wire bonds 125.

Molding material 110 may be disposed in via array 120 with distal ends 128 of wires 123 of via array 120 extending above molding material 110. Molding material 110 may encapsulate die stack 501, as well as integrated circuit die 10. An underfill 54 may be disposed between surfaces 511 and 102.

Thermal paste 42, or more particularly a layer of thermal paste 42, may be disposed in contact with distal ends 128 of wires 123 and in contact with a lower surface 142 of heat sink 43 for thermally coupling distal ends 128 of wires 123 and heat sink 43. Thermal paste 42 may be deposited or otherwise disposed on upper surface 141 of molding material 110, which is above and over die stack 501 in order to be in contact with distal ends 128 of wires 123. Again, heat sink 43 may be located or disposed above, including without limitation in contact with, distal ends 128 of wires 123. However, as illustratively depicted, distal ends 128 of wires 123 may, though need not, come into direct contact with lower surface 142 of heat sink 43. Effectively, thermal paste 42 may thermally conduct heat from wires 123 to heat sink 43, and wires 123 may thermally conduct heat from integrated circuit die 10 to thermal paste 42.

Optionally, molding material 110 need not be disposed over upper surface 521 of die stack 501. In such an implementation, thermal paste 42 may be in direct contact with upper surface 521 of die stack 501 for thermal conduction of heat away therefrom to heat sink 43. Furthermore, heat sink 43 as described herein may be any heat sink, which conventionally is a thermally conductive metal or metal alloy, and which may or may not have associated therewith a fan, a fluid circulating system, and/or other heat removal system.

An optional passivation layer and a metalization layer may be used with integrated circuit die 10, as previously described but not repeated for purposes of clarity. Additionally, via array 120 may include more than one via array, such as via arrays 121 and 122 as previously described but not repeated for purposes of clarity.

FIG. 6 is a flow diagram depicting an exemplary process 600 for formation of a microelectronic device 100, such as previously described. At 601, a substrate may be obtained, where such substrate has a first upper surface and a first lower surface. Such substrate may be an interposer 40 or a package substrate 41.

At 602, an integrated circuit die 10 is obtained having a second upper surface and a second lower surface. At 603, such first upper surface of such substrate is interconnected, such as with solder balls 53 or microbumps 52, to such second lower surface of such integrated circuit die 10 for electrical conductivity therebetween. At 604, a via array 120 may be formed having proximal ends of wires thereof coupled to such second upper surface for conduction of heat away from such integrated circuit die 10.

Optionally, prior to forming via array 120, at 611 a passivation layer may be formed on such second upper surface of such integrated circuit die. At 612, a metalization layer may be plated on such passivation layer for wire bonds for coupling such proximal ends of such wires of such via array to such second upper surface for such thermal conduction.

After forming via array 120 at 604, at 605 a molding material 110 may be deposited in such via array 120 with distal ends of such wires of such via array extending at least to a superior surface of such molding material 110 deposited. At 606, a thermal paste 42 may be applied for contact with such distal ends of such wires for thermally coupling such distal ends of such wires with a heat sink 43. At 607, a lower surface of such heat sink may be placed onto such thermal paste. Such lower surface of such heat sink 43 may be located above such distal ends of such wires for contact with a lower surface of such heat sink 43.

While the foregoing describes exemplary embodiment(s) in accordance with one or more aspects of the invention, other and further embodiment(s) in accordance with the one or more aspects of the invention may be devised without departing from the scope thereof, which is determined by the claim(s) that follow and equivalents thereof. Claim(s) listing steps do not imply any order of the steps. Trademarks are the property of their respective owners. 

What is claimed is:
 1. A microelectronic device, comprising: a substrate having a first upper surface and a first lower surface; an integrated circuit die having a second upper surface and a second lower surface; interconnects coupling the first upper surface of the substrate to the second lower surface of the integrated circuit die for electrical communication therebetween; a via array having proximal ends of wires thereof coupled to the second upper surface for conduction of heat away from the integrated circuit die; and a molding material disposed in the via array with distal ends of the wires of the via array extending at least to a superior surface of the molding material.
 2. The microelectronic device according to claim 1, further comprising: a metalization layer disposed over the second upper surface of the integrated circuit die for coupling the proximal ends of the wires of the via array to the second upper surface for the conduction; a heat sink disposed above the distal ends of the wires; and a thermally conductive material disposed in contact with the distal ends of the wires and a lower surface of the heat sink for coupling the distal ends of the wires and the heat sink for thermal conductivity.
 3. The microelectronic device according to claim 2, wherein the wires are first wires, the microelectronic device further comprising second wires coupling the second upper surface to the first upper surface of the substrate for the conduction.
 4. The microelectronic device according to claim 1, wherein: the proximal ends of the wires of the via array are first proximal ends of first wires of a first via array, respectively; and the microelectronic device further comprising a second via array having second proximal ends of second wires thereof coupled to the second upper surface for the conduction of heat away from the integrated circuit die.
 5. The microelectronic device to claim 4, wherein the first via array is denser than the second via array.
 6. The microelectronic device to claim 5, wherein the first via array is disposed over a hot spot of the integrated circuit die.
 7. The microelectronic device to claim 6, wherein: the distal ends of the first wires of the first via array are first distal ends of first wires of a first via array, respectively; and second distal ends of the second wires of the second via array are more widely dispersed than the first distal ends of the first wires of the first via array.
 8. The microelectronic device to claim 7, wherein the first distal ends of the first wires of the first via array and the second distal ends of the second wires of the second via array do not come into contact with the lower surface of the heat sink.
 9. The microelectronic device to claim 1, wherein the substrate is a package substrate.
 10. A microelectronic device, comprising: a package substrate having a first upper surface and a first lower surface; an interposer substrate having a second upper surface and a second lower surface; first interconnects coupling the second lower surface and the first upper surface to one another; an integrated circuit die having a third upper surface and a third lower surface; second interconnects coupling the second upper surface and the third lower surface to one another; a die stack coupled to the interposer substrate; wherein the die stack has a fourth upper surface higher than the third upper surface; a via array having proximal ends of wires thereof coupled to the third upper surface for conduction of heat away from the integrated circuit die; and a molding material disposed in the via array with distal ends of the wires of the via array extending at least to a superior surface of the molding material and higher than the fourth upper surface of the die stack.
 11. The microelectronic device according to claim 10, further comprising: a metallization layer disposed over the second upper surface of the integrated circuit die for wire bonds coupling the proximal ends of the wires of the via array to the third upper surface for the conduction; a heat sink disposed above the distal ends of the wires; and a thermally conductive material disposed in contact with the distal ends of the wires and a lower surface of the heat sink for coupling the distal ends of the wires and the heat sink for thermal conductivity.
 12. The microelectronic device according to claim 11, further comprising a passivation layer disposed on the second upper surface of the integrated circuit die, wherein the metalization layer is disposed on the passivation layer.
 13. The microelectronic device according to claim 10, wherein: the proximal ends of the wires of the via array are first proximal ends of first wires of a first via array, respectively; and the microelectronic device further comprising a second via array having second proximal ends of second wires thereof coupled to the third upper surface for the conduction of heat away from the integrated circuit die.
 14. The microelectronic device according to claim 13, wherein the first via array is denser than the second via array.
 15. The microelectronic device according to claim 14, wherein the first via array is disposed over a hot spot of the integrated circuit die.
 16. The microelectronic device to claim 13, wherein: the distal ends of the first wires of the first via array are first distal ends of first wires of a first via array, respectively; and second distal ends of the second wires of the second via array are more widely dispersed than the first distal ends of the first wires of the first via array.
 17. The microelectronic device to claim 16, wherein the first distal ends of the first wires of the first via array and the second distal ends of the second wires of the second via array do not come into contact with the lower surface of the heat sink.
 18. A method for formation of a microelectronic device, comprising: obtaining a substrate having a first upper surface and a first lower surface; obtaining an integrated circuit die having a second upper surface and a second lower surface; interconnecting with interconnects the first upper surface of the substrate to the second lower surface of the integrated circuit die for electrical conductivity therebetween; forming a via array having proximal ends of wires thereof coupled to the second upper surface for conduction of heat away from the integrated circuit die; and depositing molding material in the via array with distal ends of the wires of the via array extending at least to a superior surface of the molding material.
 19. The method according to claim 18, further comprising: forming a passivation layer on the second upper surface of the integrated circuit die; plating a metalization layer on the passivation layer for wire bonds for coupling the proximal ends of the wires of the via array to the second upper surface for the conduction; applying a thermally conductive material for contact with the distal ends of the wires for thermally coupling the distal ends of the wires with a heat sink; and placing a lower surface of the heat sink onto the thermally conductive material; wherein the lower surface of the heat sink is located above the distal ends of the wires for contact with a lower surface of the heat sink.
 20. The method according to claim 19, wherein the proximal ends of the wires of the via array are first proximal ends of first wires of a first via array, respectively; and the method further comprising forming a second via array having second proximal ends of second wires thereof coupled to the second upper surface for the conduction of heat away from the integrated circuit die. 